The statements in this section merely provide background information related to the present disclosure and do not constitute prior art.
In recent years, as a smart phone has been vitalized, various sorts of applications have appeared. Among the applications, an application such as a messenger requiring functions of receiving and sending packets is increasing. In particular, in a case of an application in the form of the messenger, a corresponding server should always know a location of a user terminal device loaded with the application for the packet receiving function, and to this end, a session is maintained between the terminal device and a server.
A push notification (hereinafter, referred to as PN) technology of notifying, at a time of data reception, the fact that a message has been transferred to an application requiring the reception is being applied to the application in the form of the messenger. That is, the PN technology refers to a technology by which, when a loaded application of user terminal device A is connected with a server and transfers to the server the fact that there is a message which will be sent to user terminal device B, the server searches for a session of user terminal device B and transfers to user terminal device B a push notification that there is a message which user terminal device A has sent, and user terminal device B can identify the message which user terminal device A has sent when recognizing the push notification.
Moreover, in the case of the application in the form of the messenger, a keep-alive message is transferred from the terminal device to the server according to a predetermined period for the sake of maintaining the session between the terminal device and the server, and the server transfers an ACK message to the terminal device after recognizing the keep-alive message.
The inventor(s), however, has experienced that in the case of the application in the form of the messenger as described above, since the push notification and the keep-alive message are applied by using the data call, a concurrent call (or Multi-RAB) state in which a voice call and a data call are simultaneously performed is increased, and since the data call exerts a larger influence (a decrease in coverage according to an increase in required power) on a network quality than the voice call, a voice call drop is caused by the increase in the concurrent call.
Moreover, the inventor(s) has experienced that as recently there are increases in sorts and the number of the applications in the form of the messenger and the applications requiring the keep-alive message transmission using the data call for the sake of maintaining the session, an attempt for the data call connection is increased according to driving of the corresponding application to overload the network.